#include "bits/stdc++.h"

#define debug(x) cout<<#x<<": "<<x<<endl
#define rep(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for (int i=(a);i<=(b);i++)
#define all(a) (a).begin(),(a).end()
using namespace std;
typedef vector<int> VI;
typedef vector<vector<int>> VVI;
typedef long long ll;


void solve() {
#ifdef _WIN32
	istream &cin = ifstream("input.txt");
#endif

	int n, sum = 0;
	cin >> n;
	VI v(n);
	rep(i, n) {
		cin >> v[i];
		sum += v[i];
	}
	if (sum % 2 == 1) {
		cout << "impossible" << endl;
		return;
	}
	sum /= 2;

	VVI dp(n + 1, VI(sum + 1));
	rep(i, n + 1) dp[i][0] = 1;
	rep(i, n + 1) {
		rep(j, sum + 1) {
			if (i == 0) continue;
			if (dp[i - 1][j] == 1) dp[i][j] = 1;
			if (j - v[i - 1] >= 0 && dp[i - 1][j - v[i - 1]]) dp[i][j] = 1;

		}
	}
	cout << (dp[n][sum] == 1 ? "possible" : "impossible") << endl;
}




int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	solve();
	system("PAUSE");
	return 0;
}